Abstract
AEI Aquaculture Environment Interactions Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections AEI 9:21-32 (2017) - DOI: https://doi.org/10.3354/aei00212 Responses in bacterial community structure to waste nutrients from aquaculture: an in situ microcosm experiment in a Chilean fjord Lasse Mork Olsen1,*, Klaudia L. Hernández2, Murat Van Ardelan3, Jose Luis Iriarte4,5, K. Can Bizsel6, Yngvar Olsen7 1Norwegian Polar Institute, Fram Centre, 9296 Tromsø, Norway 2Facultad de Ecologia y Recursos Naturales, Universidad Andres Bello, 2520000 Viña del Mar, Chile 3Norwegian University of Science and Technology, Dept. of Chemistry, 7491 Trondheim, Norway 4Instituto de Acuicultura and Centro FONDAP de Investigación Dinámica de Ecosistemas Marinos de Altas Latitudes (IDEAL), Universidad Austral de Chile, 5480000 Puerto Montt, Chile 5COPAS-Sur Austral, Centro de Investigación Oceanográfica en el Pacífico Sur-Oriental (COPAS), Universidad de Concepción, 4030000 Concepción, Chile 6Dokuz Eylül University, Institute of Marine Sciences and Technology, Bakü Bulv. No. 100, 35340 Inciralt, Izmir, Turkey 7Norwegian University of Science and Technology, Dept. of Biology, 7491 Trondheim, Norway *Corresponding author: lasse.mork.olsen@npolar.no ABSTRACT: Chilean salmon farms release inorganic nutrients excreted by the fish into the surrounding water in Patagonian fjords. The objective of this experiment from the Comau Fjord (42.2° S) in southern Chile was to study how increased input of ammonium (NH4) and phosphate (PO4) from salmon farms might affect the community structure of bacteria in surface waters where fish farms are located. We used microcosms (35 l) with NH4-N and PO4-P added to the natural seawater in a gradient of nutrient-loading rates, with the same N:P ratio as in salmon aquaculture effluents. Additionally, we measured bacterial community structure at different depths in the Comau Fjord to assess the natural variation to compare with our experiment. We used denaturing gradient gel electrophoresis (DGGE) to create 16S rDNA fingerprints of the bacterial communities and monitored biological and environmental variables (chlorophyll a, inorganic nutrients, pH, microbial abundance). The nutrient-loading rate had a significant impact on the bacterial community structure, and the community dissimilarity between low and high nutrient additions was up to 78%. Of the measured environmental variables, phytoplankton abundance and increased pH from photosynthesis had a significant effect. We observed no significant changes in bacterial diversity, which remained at the same level as in the unmanipulated community. Thus, the bacterial community of the fjord was not resistant, but resilient within the time frame and nutrient gradient of our experiment. KEY WORDS: Aquaculture · Eutrophication · Microbial community · Bacterial diversity · Chile · Patagonia Full text in pdf format PreviousNextCite this article as: Olsen LM, Hernández KL, Ardelan MV, Iriarte JL, Bizsel KC, Olsen Y (2017) Responses in bacterial community structure to waste nutrients from aquaculture: an in situ microcosm experiment in a Chilean fjord. Aquacult Environ Interact 9:21-32. https://doi.org/10.3354/aei00212 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in AEI Vol. 9. Online publication date: January 31, 2017 Print ISSN: 1869-215X; Online ISSN: 1869-7534 Copyright © 2017 Inter-Research.
Highlights
Cage aquaculture of fish releases inorganic nitrogen (N) in the form of ammonium (NH4) and inorganic phosphorus (P) in the form of phosphate (PO4) excreted by the fish to the surrounding water
Nitrate and ammonium were almost depleted throughout the experiment, with a slightly higher ammonium concentration measured in the highest addition treatments
The nutrient-loading rate had a significant effect on the bacterial community structure of the Comau Fjord, and the increase in phytoplankton abundance, and pH increase as a consequence, were the strongest forcing factors
Summary
Cage aquaculture of fish releases inorganic nitrogen (N) in the form of ammonium (NH4) and inorganic phosphorus (P) in the form of phosphate (PO4) excreted by the fish to the surrounding water. Possible regulating factors for bacterial community structure are inorganic nutrients (Fisher et al 2000), the type and availability of organic substrate (Cottrell & Kirchman 2000, GómezConsarnau et al 2012), mortality from predation and virus infection (Langenheder & Jürgens 2001, Töpper et al 2013), physicochemical variables like temperature, salinity and pH (Krause et al 2012, Campbell & Kirchman 2013) and possibly other biotic interactions such as allelopathy (Long & Azam 2001). This is likely to be the result of a complex response, with bottom-up effects from increased productivity and top-down effects from predation and some of the other regulating factors mentioned above (Lebaron et al 1999, Bohannan & Lenski 2000, Schäfer et al 2001, HornerDevine et al 2003)
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